Railway track circuit apparatus



Feb. 2, 1943. I A. E. DODD 2,309,757v

RAILWAY TRACK CIRCUIT APPARATUS Filed July 51, 1941 INVENTOR Amlzufl Dodd.

BY 5 Z HIS ATTORNEY Patented Feb. 2, 1943 UNITED STATES PATENT OFFICE Union Switch & Si

gnal Company, Swissval'e,

Ia., a corporation of Pennsylvania Application July 31, 1941, Serial No. 404,824

4 Claims.

My invention relates to railway track circuit apparatus and it has particular reference to the organization of such apparatus into novel and improved railway track circuits. More particularly, my invention relates to railway track circuits incorporating apparatus arranged to be independent of variations in track ballast resistance.

Railway track circuits have ben proposed heretofore incorporating relays arranged to effect operation of their contacts only in response to rapid changes in the track circuit energy received by the relays, as when a train enters or leaves a track circuit, but not in response to gradual changes in the relay energization effected due to changes in track ballast resistance caused by atmospheric conditions, etc. In such systems, the relays employed generally have been designed to operate their contacts in response to a predetermined decrease in energy in the relay, independently of existing ballast resistance conditions, while operation of the contacts in response to an increase in energy in the relay is made dependent upon the ballast conditions existing at the time the relay operated its contacts due to a decrease in energy available. When a train enters such a circuit adjusted for extremely dry (or high resistance) ballast, and during the occupancy of the section, the ballast resistance varies and becomes lower due, for example, to an extremely heavy rainfall, there is a possibility that the relay might not operate and hence it might fail to close its contacts after the train vacates the circuit, because the increased proportion of the current leaking across the ballast might cause the energy available at the relay to remain below the value required to effect operation of the relay contacts.

In view of the above-mentioned and other important considerations, it is an object of my present invention to provide novel and improved track circuit apparatus arranged in such manner as to operate its contacts in response to a predetermined change in energy received by the relay, conditions.

Another object is the provision, in a railway track circuit, of a relay incorporating novel and improved means for causing operation of the relay contacts due to a change in energy supplied to the relay, and which operation is caused to be independent of ballast conditions existing at the time the change in energy occurs.

A further object is the provision of novel and improved railway track circuit apparatus havindependently of existing track ballast ing a member which adjusts its position to the energy level available in the circuit, and which member is coupled to means for causing operation of contacts only in response to a rapid movement of the member but not in response to slow movements of the member.

An additional object is the provision of novel and improved electrical relays particularly adapted for use in railway track circuits.

Another object is to provide a novel and improved form of railway track circuit apparatus of the type described and claimed in an application for Letters Patent, Serial No. 404,823, filed July 31, 1941, by Norman F. Agnew and Paul N. Martin, and assigned to the assignee of the present application.

The above-mentioned and other important objects and characteristic features of my invention which will become readily apparent from the following description, are attained in accordance with my invention by incorporating into a track circuit a relay responsive only to abrupt changes in the energy received by the relay and comprising a movable element biased to one position and urged by the force of the relay winding against that bias to a position corresponding to the energy received by the relay winding from the track rails, contact means operated by the movable element, and inertia means cooperating with the movable element to cause operation of the contact means only in response to an abrupt and large change in energy received by the winding from the track circuit occasioned by a train entering or leaving the section, the inertia means being biased to one position and urged by the movable element away from its ibiased position only in response to a sudden movement of the movable element caused by an abrupt change in energy received by the relay winding.

I shall describe one form of railway track circuit apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawing, Figs. 1 and 2 are diagrammatic views illustrating one form of apparatus embodying my invention. Fig. 3 is a diagrammatic view showing a modification of a portion of the apparatus represented in Fig. 1. In each of the several views, similar reference characters have been employed to designate corresponding parts.

Referring to the drawing, the reference characters l and la designate the track rails of a stretch of railway track divided by insulated joints 2 into an insulated track section D-E. Section D-E is provided with a track circuit comprising a suitable source of energy, such as a track transformer TT having its primary winding connected to a suitable source of alternating current, such as a generator not shown, and having its secondary winding connected across the track rails at one end of the section, and a track relay TR connected across the rails at the other end of the section. Relay TR is of the type arranged to operate its contacts in response to abrupt and relatively large changes in the energization of the relay winding but not in response to gradual changes in the relay energization, and as shown, comprises an electromagnet 5 having a G-shaped core 6 provided with a coil 1 supplied with energy from the rails of section D-E. Disposed in the magnetic field of the electromagnet between the pole pieces of core 5 is a movable element in the form of an aluminum or copper vane 8 mounted on a shaft 9 journaled in side members in. The vane 8 is biased, as by a counterweight H secured to shaft 9, to assume a position dependent upon the energization of electromagnet 5. That is to say, when the electromagnet is deenergized, vane 8 is caused to assume a position corresponding to the pendant position of counterweight ll. When electromagnet 5 is energized, the vane is caused to rotate to a position wherein the torque exerted by weight II on the shaft just balances the torque due to the induced current in the vane. As the energization of the electromagnet is increased the vane is caused to rotate against the gravity bias of counterweight II to a new position corresponding to the new level of energization of the electromagnet 5, and similarly, if the energization of electromagnet 5 decreases, the vane rotates to a corresponding position in response to the gravity bias of weight H.

Relay TB is provided in the usual manner with neutral contacts [4 and I5, controlled by vane 8 so as to be closed whenever electromagnet 5 is energized at the level corresponding to an unoccupied section and minimum ballast conditions. The contacts preferably are controlled by vane 8 through the medium of a link member 16 incorporating a spring i! so arranged as to permit the vane to move freely after the neutral contacts l4 and [5 are closed and compressed.

Relay TR is further provided with means for causing operation of a set of contacts only in response to a sudden change in energization of the relay but not in response to gradual and slight changes of the energization. These means, as shown, comprise a C-shaped magnetizable member, or permanent magnet 20, pivoted on a pin 2| journaled in members 22 secured to the frame, disposed with vane 8 between its pole pieces. The magnet 20, although free to move and rotate about pin 2|, is relatively heavy and hence has a relatively large inertia. An insulated contact member 23 secured to magnet is adapted to engage either fixed contact finger 24 or 25 according as member 20 is caused to rotate to the left or to the right, as viewed in the drawing, about pivot 2!.

Relay TR operates as follows: When section D--E is unoccupied and electromagnet 5 is energized, vane 8 assumes a position corresponding to the level of energization of the electromagnet. Neutral contacts l4 and I5 are closed, and member 20 assumes a pendant position wherein contact engaging member 23 is out of engagement with contact fingers 24 and 25. An auxiliary stick relay TRS is energized over an obvious circuit extending from terminal B through contact 25-25 of relay TR, and front contact 21 and the winding of relay IRS to terminal C. Contacts operated by relay 'I'RS may be employed, either alone or in series with neutral contacts l4 and I5 of relay TR, for controlling the usual functions, such as signals, locks, etc., usually controlled by track circuit apparatus.

With the apparatus in the condition described. gradual and slight changes in the energization of the electromagnet, caused by changes in track ballast resistance conditions in section D-E, cause vane 8 to rotate slowly to a position dependent upon the level of energization of magnet 5. As pointed out hereinbefore, link member l5 permit-s such movement of vane 8 to take place without interference due to the closed neutral contacts, and since these movements of the vane are relatively slow, they do not cause member 20 to operate either of its contacts.

When, however, there is a sudden and relatively large change in the energization of magnet 5, as for example when a train enters the section and shunts the electromagnet, vane 8 is caused to move rapidly toward its deenergi'zed position. The rapid rotation of the vane in the field of magnet 20 causes eddy currents to be induced in the vane, tending to retard its motion. Magnet 20 is free to rotate, hence the reaction to this retarding force, acting on the magnet, causes the lower end of magnet 20 to move in the direction of the rotation of the vane, and member 20 rotates about pivot 2| to cause member 23 to engage contact finger 25 to open contact 25-26 and release relay TRS. After the vane assumes its deenergized position, member 20 drops to its normal position, as shown.

Relay TR. remains in the condition described during the interval that the section is occupied. Should, however, the ballast resistance change during the time the section is occupied, vane 8 might assume different positions in accordance with the ballast resistance conditions in the section, but since the ballast resistance changes ocour very slowly, any movement of the vane caused by a change in the ballast resistance would, of course, occur at a relatively slow rate and would not cause operation of the contacts operated by member 20. Likewise, small changes in the resistance of the train shunt as the train passes through the section might cause rotation of vane 8, but such rotation would not be of suflicient magnitude to cause operation of the contacts associated with member 20.

When, however, there is another sudden and relatively large change in the energization of electromagnet 5, as when the train vacates section D-E and removes the train shunt, vane 8 is rapidly rotated to a position depending upon the energization of the electromagnet. This rotation of the vane in the field of magnet 20 induces eddy currents in the vane and the reaction force on magnet 20 causes its lower end to move in the direction of the vane rotation. The parts are proportioned so that the motion of vane 8 caused when a section becomes unoccupied is sufilcient to cause member 23 to engage contact finger 24, thereby completing an obvious pickup circuit for stick relay TRS. Relay TRS thereupon picks up and closes its front contact 21 to complete its previously traced stick circuit.

After the vane assumes its position of correspondence with the energization of the electromagnet 5, magnet 20 assumes its normal position,

as shown, and contact 23-24 opens. The apparatus is then restored to its normal condition as represented in the drawing.

In a modified form of relay TR, shown in Fig. 3, member 20 is provided with a toggle action by means of a ball 30 secured to member 20 and a plunger 3| actuated by a spring 32. When the member is operated to either extreme position due to a rotation of vane 8, member 20 is retained in such a position by virtue of the toggle until the vane is caused to depress the toggle and swing to its other extreme position. By use of the toggle, the stick circuit control of relay 'IRS may be eliminated, with relay TRS energized over contact 2324 whenever member 23 is in its normal (picked-up) position, as shown, and the relay is deenergized when member 20 swings to its other position upon vane 8 rotating to its deenergized position.

From the foregoing, it is readily apparent that I have provided track circuit apparatus incorporating a relay arranged to operate its contacts in response to abrupt and relatively large changes in energy received by the relay, but not in response to gradual and relatively small changes in the energization of the relay. In addition, it is apparent that operation of such contacts is attained by a magnetic coupling independently of a mechanical connection between the movable member and the biased contact operating member.

Although I have herein shown and described only one form of track circuit apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a vane type relay having a vane pivoted for rotation in the field of an electromagnet, said vane being arranged to assume a rotated position dependent upon the energization of said electromagnet, the combination of a second magnet disposed with said vane in its field, means for pivoting said second magnet, a relay normally energized over a stick circuit including its own front contact and a contact normally closed but opened when said second magnet is caused to swing in one direction in response to a relatively rapid movement of said vane to its normal or released position, and a pick-up circuit for said relay completed over a contact closed when said second magnet is caused to swing in the opposite direction in response to a relatively rapid movement of said vane to its rotated position.

2. In combination with an electromagnet, a rotatably mounted conducting member biased to one position and rotated against its bias by the force of said electromagnet to a position corresponding to the energy available in said electromagnet, a second magnet disposed with said member in its field, said second magnet being pivoted for rotation to either of two extreme positions and having means for retaining said second magnet in either of its extreme positions until caused to operate therefrom in response to a sudden movement of said member in the field of said second magnet, and contacts operated by said second magnet.

3. An alternating current type relay for use in railway track circuits, said relay comprising an electromagnet, a vane rotatably mounted in the field of said electromagnet, biasing means operatively connected with said vane for limiting rotation thereof to a position dependent upon the energization of said electromagnet, contacts operatively connected with said vane and operated from an open to a closed position when said vane operates to a given position, said operative connection of said contacts with said vane including means which freely permits further rotation of said vane while maintaining said contacts closed, a second magnet disposed with said vane in its field and pivoted for movement in response to the reaction forces established when said vane moves in its field, and other contacts operatively connected with said second magnet, said second magnet having a relatively large inertia whereby to effect operation of said other contacts when a rapid vane movement occurs but not when said vane moves slowly to adjust its position to slight or gradual changes in the energization of said electromagnet.

4. An alternating current type relay for use in railway track circuits, said relay comprising an electromagnet, a vane rotatably mounted in the field of said electromagnet, biasing means operatively connected with said vane for biasing said vane to a normal position and for limiting rotation thereof to a position dependent upon the energization of said electromagnet, contacts operatively connected with said vane in such manner that operation of said contacts is effected when said vane rotates to a given predetermined position and such contacts remain operated while freely permitting further rotation of said vane to occur, a second magnet pivoted for rotation and disposed with said vane in its field, and other contacts operatively connected with said second magnet, said second magnet having a relatively large mass whereby rotation of said magnet is effected to cause operation of said other contacts whenever said vane moves rapidly toward or away from its biased normal position but not when said vane moves slowly to adjust its position to gradual changes in the energization of said electromagnet.

ARTHUR E. DODD. 

